Injection device, control valve and method for injecting fluid

ABSTRACT

The invention concerns an injection device having a fluid port ( 10 ), a control valve ( 12 ), a setting element ( 14 ), by way of which a region of a first face ( 24 ) of the control valve ( 12 ) can be acted upon with force, and a control chamber ( 30 ) provided on the side of a second face ( 26 ) of the control valve ( 12 ), whereby a compensating chamber ( 28 ) is provided on the side of the first face ( 24 ) of the control valve ( 12 ), the compensating chamber ( 28 ) is partially limited by the first face ( 24 ) of the control valve ( 12 ), and the compensating chamber ( 28 ) communicates with the control chamber ( 30 ). The invention also concerns a control valve as well as a method for injecting fluid.

RELATED ART

[0001] The invention concerns an injection device having a fluid port, acontrol valve, a setting element, by way of which a region of a firstface of the control valve can be acted upon with force, and a controlchamber provided on the side of a second face of the control valve. Theinvention further concerns a control valve having a valve seat, a firstface that faces a compensating chamber, and a second face that faces acontrol chamber. The invention further concerns a method for injectingfluid, in which a first face of a control valve is acted upon with forceby way of the extension of a setting element, a control chamber isdischarged by way of a valve seat of the control valve, and an injectionnozzle opens.

[0002] Devices according to the general class as well as a methodaccording to the general class are known. Solenoid valves orpiezoactuators are generally provided as setting elements. Whilesolenoid valves, by themselves, can provide a stroke that is sufficientfor control, a power-travel pressure intensification is generallyrequired when piezoactuators are used, which is commonly accomplishedhydraulically. The motion of the piezoactuator is transferred to thecontrol valve by way of the hydraulic power-travel pressureintensification, so that the switching state of the control valvechanges. As a result, the pressure conditions in a control chamberchange, which, finally, opens an injection nozzle.

[0003] Injection devices are often constructed in such a way that, in aninitial state, a high pressure—in the neighborhood of the pressure of acommon-rail system—is present in the control chamber. A characteristicfeature of such a common-rail system or storage injection system is thefact that pressure generation and injection are decoupled. The injectionpressure is generated independently of the engine speed and rate ofinjection, and it waits in the “rail” (fuel accumulator) for injection.In current systems, the pressure in the common rail is in the range ofbetween 1000 and 2000 bar, with higher pressures coming into increasinguse. To open the injection nozzle, the control chamber is discharged viaactivation of the control valve, so that a reduced pressure acts uponthe valve control piston. As a result, the injection nozzle can open. Toclose the injection nozzle, the control valve is returned to its initialstate, whereby high pressure forms in the control chamber once more. Asa result, the injection nozzle closes due to the force that acts on thevalve control piston.

[0004] Depending on the arrangement of the control valve within theinjection device, the speed at which the injection nozzle closes may beslower than desired, and the construction of the injection device may beless than compact. Moreover, considerable forces may be required toactuate the control valve by means of the setting element.

ADVANTAGES OF THE INVENTION

[0005] The invention is based on the injection device according to thegeneral class in that a compensating chamber is provided on the side ofthe first face of the control valve, that the compensating chamber ispartially limited by the first front face of the control valve, and thatthe compensating chamber communicates with the control chamber. By wayof this arrangement, the pressure present in the control chamber—incommon-rail systems, this is the rail pressure—is transferred to thecompensating chamber. This pressure corresponds to a force that acts onthe first face of the control valve. The setting element therefore needonly exert a reduced force on the control valve in order to actuate it.

[0006] The control valve preferably comprises at least one channel thatconnects the compensating chamber with the control chamber. The transferof pressure from the control chamber into the compensating chamber cantherefore be carried out by way of a simple action.

[0007] In a first state, a valve seat of the control valve preferablyseals off the control chamber from a leakage system. High pressure cantherefore form in the control chamber, which keeps the injection nozzlein a closed state or moves the injection nozzle into a closed state.

[0008] It is an advantage thereby if elastic means are provided thathold the valve seat of the control valve closed. By this means, adefined state of the control valve is ensured when the setting elementis retracted.

[0009] In a second state, the control valve preferably connects thecontrol chamber with a leakage system. If the control valve is thereforeacted upon with force by the setting element and transferred to a secondstate, the pressure can escape from the control chamber into the leakagesystem. This makes it possible for the injection nozzle to open.

[0010] In a preferred arrangement, the control chamber is connected tothe leakage system by way of the channel and a drainage damping valve.As a result of the interplay with the other flow conditions within thesystem, a drainage damping valve makes it possible to influence theopening time of the injection nozzle. The provision of this drainagedamping valve in conjunction with the channel—by way of which thecontrol chamber communicates with the compensating chamber—isparticularly economical and space-saving, so that a compact constructionof the control valve is encouraged.

[0011] The control valve preferably comprises a surface area in thechamber around the valve seat that can be acted upon with force by thepressure generated in the control chamber. By this means, a furtherforce equalization takes place, and the force to be applied by thesetting element on the control valve is reduced once more.

[0012] It is particularly advantageous thereby if the effective firstface of the control valve, together with the effective surface area inthe space around the region of the valve seat, basically corresponds tothe effective second face. In this context, “effective surface area”refers, in each case, to a surface area that is perpendicular to thedirection of movement of the control valve. If the effective second faceis acted upon with force by the total pressure in the control chamber,this force is equalized by the sum of forces that act on the first face,on the one hand, and on the surface area in the chamber around the valveseat, on the other. The effective surface area that is available for theforce equalization is therefore only reduced around the surface area ofthe first face upon which the setting element acts. This surface areahas a diameter of 1.8 mm, for example, and is extremely small comparedto the effective second face. A satisfying force equalization istherefore achieved.

[0013] Further advantages of the invention result from the fact that, ina first state of the control valve, and in a second state of the controlvalve, the fluid port is sealed off from the control chamber. In thesestates of the control valve, the control chamber is connected to thefluid port only by way of a port damping valve. This makes it possiblefor pressure reduction to take place by way of the connection of thecontrol chamber with the leakage system.

[0014] It is then particularly advantageous if, in a third state of thecontrol valve, a connection is established between the fluid port andthe control chamber. When the control valve enters the third switchingstate, therefore, it becomes possible for the pressure in the controlchamber to increase abruptly, which causes the injection nozzle to closeparticularly rapidly.

[0015] The control chamber and the fluid port are preferably sealed offand connected, respectively, by means of a control sleeve that can bemoved by the control valve. During the first and second switchingstates, the control sleeve is located in its control sleeve seat, by wayof which the fluid port is sealed off from the control chamber. If thecontrol valve moves into its third switching state, however, the controlsleeve is lifted out of its control sleeve seat, and the fluid port andcontrol chamber are suddenly connected. This results in the abruptincrease of pressure in the control chamber, which makes theadvantageously rapid closing of the injection nozzle possible.

[0016] The setting element is preferably a piezocontroller.Piezocontrollers have proven to be effective in injection devices due totheir compact construction and reliability. Moreover, the implementationof multiple switching states of the control valve is made possible byvarying the electrical control variables of the piezoconnector inreliable fashion.

[0017] It is advantageous to provide a hydraulic power-travel pressureintensifier, by way of which the setting element acts upon the controlvalve with force. As a result, the various switching states of thecontrol valve can be achieved even when the travel of thepiezocontroller or piezoactuator is minimal.

[0018] The fluid port is preferably connected to a common-rail system.Since the common rail always provides high pressure regardless of theinjection process, the injection nozzle can be closed particularlyrapidly.

[0019] The control chamber is preferably connected to the fluid port byway of a port damping valve. The opening speed of the injection nozzlecan therefore be influenced by way of a suitable design of the portdamping valve with regard for other flow conditions, in particular by adrainage damping valve.

[0020] It is advantageous when the control valve projects into thecontrol chamber. This makes a particularly compact design of theinjection device possible.

[0021] The invention also concerns a control valve that is based on thecontrol valve according to the general class in that a chamber aroundthe valve seat, the compensating chamber, and the control chambercommunicate with each other. By this means, the control valve isforce-equalized, so that only minimal forces need by applied by thesetting element to actuate the control valve.

[0022] The control chamber and the compensating chamber preferablycommunicate by way of a channel provided in the control valve. This is aparticularly simple solution for providing the force equalizationaccording to the invention.

[0023] It is particularly advantageous when the chamber around the valveseat is connected with the channel by way of a damping valve. Thecontrol valve must therefore be inserted in such a fashion that acontrol chamber communicates with the chamber around the valve seat byway of the channel and a damping valve. This solution is particularlyeconomical. On the other hand, a damping valve makes it possible toutilize the flow conditions in the control valve for other controlpurposes.

[0024] The effective first face, together with the effective surfacearea in the chamber around the valve seat, preferably correspondsbasically to the effective second face. In this context, “effectivesurface area” refers to the surface component arranged perpendicularlyto the direction of movement of the control valve. An extensive forceequalization therefore takes place.

[0025] The invention is based on the method according to the generalclass in that at least one part of the first face of the control valveis acted upon with force by the pressure of a fluid, so that the forceacting on the second face of the control valve is at least partiallyequalized. It is therefore not necessary to apply the entire forceacting on the second face of the control valve using the settingelement.

[0026] The force acting on the second face is preferably equalized aswell by the fact that a surface area in the region of the valve seat isacted on with force by the pressure of a fluid. As a result of thisadditional force equalization, the force to be applied by the settingelement can be reduced once more.

[0027] The method according to the invention is preferably furtherdeveloped in that the setting element is extended further after thecontrol chamber is discharged, that, as a result of the furtherextension of the setting element by the control valve, a control sleeveis lifted out of its control sleeve seat and moved, that the moving ofthe control sleeve causes pressure to be applied to the control chamber,and that the pressure in the control chamber causes the injection nozzleto close. The injection nozzle is therefore not closed by the retractionof the setting element, but rather by a further extension. The pressurein the control chamber must not increase by way of the port dampingvalve; given the speed at which the pressure increases, this can havenegative consequences. Rather, it can increase suddenly by way of thecontrol sleeve seat via the connection with the fluid port. This causesthe injection nozzle to close particularly rapidly.

[0028] After the injection nozzle closes, the setting element ispreferably retracted, and the control sleeve and the control valvereturn to the control sleeve seat or the valve seat, respectively. Thisreturning of the control sleeve and the control valve therefore takesplace independently of the actual injection process, which leads to anadvantageous decoupling of the various processes within the valve.

[0029] It is preferable if the control chamber is not discharged whilethe control sleeve and the control valve are returning to the controlsleeve seat and the valve seat, respectively, as this could cause theinjection nozzle to open. This can be achieved either by way of theratios of the forces acting on the moveable elements and, therefore, byway of the order in which the elements return to their seats, or it canbe achieved by way of switching processes that are rapid in comparisonto the flow processes.

[0030] The invention is based on the surprising finding that aforce-equalized control valve offers numerous advantages. On the onehand, for example, the force to be applied by the setting element isreduced and, on the other hand, a compact construction of the injectiondevice is made possible by the fact that the control valve projects intothe control chamber. A further advantage is the fact that a particularlyrapid closing of the injection nozzle can be made possible. All of theseadvantages are realized in particular when it is used in a common-railsystem.

DIAGRAM

[0031] The invention will now be described with reference to theaccompanying diagram using a preferred embodiment as an example.

[0032]FIG. 1 is a schematic, partially exposed representation of aninjection device according to the invention.

DESCRIPTION OF THE EMBODIMENT

[0033]FIG. 1 shows an injection device according to the invention. Theinjection device is supplied with the fluid to be injected—preferablywith diesel fuel—by way of a fluid port 10. A control valve 12 iscontrolled by a setting element 14, preferably a piezoactuator, by wayof a hydraulic pressure intensifier 16. The control valve 12 comprises avalve seat 18. In the state shown, the valve seat separates a chamber 20from a leakage system 22. The control valve 12 also comprises a firstface 24 and a second face 26. The first face 24 partially limits acompensating chamber 28. The second face 26 projects into a controlchamber 30. The compensating chamber 24 is connected to the controlchamber 30 by way of a channel 32. A drainage damping valve 34 joins thechannel 32, which connects the channel 32 and, therefore, thecompensating chamber 28 and the control chamber 30 with the chamber 20around the valve seat 18.

[0034] In the state shown, the control chamber 30 is filled with thepressure provided via the fluid port 10 and a port damping valve 36. Itis preferably made available by a common rail. This pressure acts uponthe valve control piston 38 with force, so that the injection nozzle 40is closed.

[0035] When the setting element 14 is actuated, the control valve 12 isactuated by way of the hydraulic pressure intensifier 16. As a result,the control valve 12 establishes a connection between the chamber 20around the valve seat 18 and the leakage system 22. The pressure in thecontrol chamber 30 can thereby be reduced via the channel 32 and thedrainage damping valve 34. The valve control piston 38 is relieved, andtravel-controlled opening of the injection nozzle 40 takes place.

[0036] Since the compensating chamber 28, the chamber 20 around thevalve seat 18, and the control chamber 30 communicate by way of thechannel 32 and the drainage damping valve 34, force equalization takesplace. Due to the pressure of the fluid, a force acts on the face 24 ofthe control valve in the compensating chamber 28, reduced by a surfacearea that corresponds to the diameter d₁ indicated in the diagram. Inthe chamber 20 around the valve seat 18, the fluid pressure also causesa force to act on a surface area that corresponds to a ring having theouter diameter d₃ and the inner diameter d₂. As a result of the fluidpressure, a force that corresponds to the diameter d₃ indicated in thediagram acts on the second face 26 of the control valve 12. As a result,the forces—except for the force corresponding to the diameter d₁—actingon the effective surface areas of the control valve 12 are equalized.This is the only force to be applied by the hydraulicpressure-intensified setting element 14 via the fluid against the forceacting on the second face 26 in the control chamber 30.

[0037] To close the injection nozzle 40, the setting element 14 is notretracted immediately. Rather, it is extended further, so that thecontrol valve 12 impacts a control sleeve 44 in the region of a groove42 running on its second face 26. At this time, this is still located inits seat 46, by way of which it seals off the fluid port 10 from thecontrol chamber 30. If the control sleeve 44 is lifted out of its seat46, however, the control chamber 30 is suddenly filled with thecommon-rail pressure introduced via the fluid port 10, and the injectionnozzle 40 therefore closes abruptly.

[0038] As a result, the setting element 14 is retracted, and the controlsleeve 44 and the control valve 12 are pushed back by springs 48, 50into the control sleeve seat 46 and the valve seat 18, respectively. Byarranging the spring forces in suitable fashion in relation to the othersystem parameters, it is possible to maintain the pressure in thecontrol chamber 30 to the extent that the valve control piston 38 is notrelieved, which would cause the injection nozzle 40 to open.

[0039] While the injection nozzle 40 is closed abruptly by the movementof the control sleeve 44, the opening behavior of the injection nozzle40 can be influenced by a suitable selection of the drainage dampingvalve 34 and/or the port damping valve 36.

[0040] The preceding description of the embodiments according to thepresent invention are intended to serve as illustrations only and arenot intended to limit the invention. Various changes and modificationswithin the framework of the invention are possible without leaving thescope of the invention or its equivalents.

1. Injection device having a fluid port (10), a control valve (12), asetting element (14), by way of which a region of a first face (24) ofthe control valve (12) can be acted upon with force, and a controlchamber (30) provided on the side of a second face (26) of the controlvalve (12), characterized in that a compensating chamber (28) isprovided on the side of the first face (24) of the control valve (12),that the compensating chamber (28) is partially limited by the firstface (24) of the control valve (12), and that the compensating chamber(28) communicates with the control chamber (30).
 2. Injection deviceaccording to claim 1, characterized in that the control valve (12)comprises at least one channel (32) that connects the compensatingchamber (28) with the control chamber (30).
 3. Injection deviceaccording to claim 1 or 2, characterized in that, in a first state, avalve seat (18) of the control valve (12) seals off the control chamber(30) from a leakage system (22).
 4. Injection device according to one ofthe preceding claims, characterized in that elastic means (50) areprovided that hold the valve seat (18) of the control valve (12) closed.5. Injection device according to one of the preceding claims,characterized in that, in a second state, the control valve (12)connects the control chamber (30) with a leakage system (22). 6.Injection device according to claim 5, characterized in that the controlchamber (30) is connected with the leakage system (22) by way of thechannel (32) and a drainage damping valve (34).
 7. Injection deviceaccording to one of the claims 3 through 6, characterized in that thecontrol valve (12) comprises a surface area in a chamber (20) around thevalve seat (18) that can be acted upon with force by the pressuregenerated in the control chamber (30).
 8. Injection device according toclaim 7, characterized in that the effective first face (24) of thecontrol valve (12), together with the effective surface area in thechamber (20) around the valve seat (18) basically corresponds to theeffective second face (26) of the control valve (12).
 9. Injectiondevice according to one of the preceding claims, characterized in that,in a first state of the control valve (12) and in a second state of thecontrol valve (12), the fluid port (10) is sealed off from the controlchamber (30).
 10. Injection device according to one of the precedingclaims, characterized in that, in a third state of the control valve(12), a connection is established between the fluid port (10) and thecontrol chamber (30).
 11. Injection device according to claim 9 or 10,characterized in that the sealing off and connecting of the controlchamber (12) and the fluid port (10) are carried out by means of thecontrol sleeve (44) that can be moved by the control valve (12). 12.Injection device according to one of the preceding claims, characterizedin that the setting element (14) is a piezoactuator.
 13. Injectiondevice according to one of the preceding claims, characterized in that ahydraulic power-travel pressure intensifier (16) is provided, by way ofwhich the setting element (14) acts upon the control valve (12) withforce.
 14. Injection device according to one of the preceding claims,characterized in that the fluid port (10) is connected with a commonrail.
 15. Injection device according to one of the preceding claims,characterized in that the control chamber (30) is connected with thefluid port (10) by way of a port damping valve (36).
 16. Injectiondevice according to one of the preceding claims, characterized in thatthe control valve (12) projects into the control chamber (30). 17.Control valve having a valve seat (18), a first face (24) that faces acompensating chamber (28), and a second face (26) that faces a controlchamber (30), characterized in that a chamber (20) around the valve seat(18), the compensating chamber (24), and the control chamber (30)communicate with each other.
 18. Control valve according to claim 17,characterized in that the control chamber (30) and the compensatingchamber (28) communicate by way of a channel (32) provided in thecontrol valve (12).
 19. Control valve according to claim 18,characterized in that the chamber (20) around the valve seat (18) isconnected with the channel (32) by way of a damping valve (24). 20.Control valve according to one of the claims 17 through 18,characterized in that the effective first face (24), together with theeffective surface area in the chamber (20) around the valve seat (18),basically corresponds to the effective second face (26).
 21. Method forinjecting fluid, in which a first face (24) of a control valve (12) isacted upon with force by the extension of a setting element (14), acontrol chamber (30) is discharged by way of a valve seat (18) of thecontrol valve (12), and an injection nozzle (40) opens, characterized inthat, at least one part of the first face (24) of the control valve (12)is acted upon with force by the pressure of a fluid, so that the forceacting on the second face (26) of the control valve (12) is at leastpartially equalized.
 22. Method according to claim 21, characterized inthat the force acting on the second face (26) is also equalized by thefact that a surface area in a chamber (20) around the valve seat (18) isacted upon with force by the pressure of a fluid.
 23. Method accordingto claim 21 or 22, characterized in that, after the control chamber (30)is discharged, the setting element (14) is extended further, that, byway of the further extension of the setting element (14) from thecontrol valve (12), a control sleeve (44) is lifted out of its controlsleeve seat (46) and moved, that, due to the sliding of the controlsleeve (44), the control chamber (30) is acted upon with pressure, andthat the injection nozzle (40) is closed by way of the pressure in thecontrol chamber (30).
 24. Method according to claim 23, characterized inthat, after the injection nozzle (40) closes, the setting element (14)is retracted and the control sleeve (44) and the control valve (12)return to the control sleeve seat (46) and the valve seat (18),respectively.
 25. Method according to claim 24, characterized in that,while the control sleeve (44) and the control valve (12) are returningto the control sleeve seat (46) and the valve seat (18), respectively,the control chamber (30) is not discharged, which could cause theinjection nozzle (40) to open.